Strapping track assembly and methods of using the same

ABSTRACT

The present description discusses apparatuses and methods for applying straps around a bundle of objects. The apparatus includes a track assembly extending substantially about a strapping station. The track assembly is adapted to receive a strap and to release the strap during a tensioning operation. Strap can be fed through the track assembly without damaging the strap.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims the benefit under 35 U.S.C. § 119(e) of U.S.Provisional Patent Application No. 60/921,022 filed Mar. 30, 2007, whichis incorporated herein by reference in its entirety.

BACKGROUND

1. Technical Field

The present invention relates to strapping apparatuses and methods forapplying straps around bundles of objects. More particularly, theinvention relates to strapping track assemblies for strappingapparatuses and methods of using the same.

2. Description of the Related Art

Strapping machines for applying flexible straps around bundles ofobjects have been developed in recent years and are disclosed in U.S.Pat. No. 5,560,180; U.S. Pat. No. 6,363,689; and U.S. Patent ApplicationPublication No. 2002/0116900 A1. A conveyor often conveys a bundle ofobjects to a strapping station where straps are automatically appliedbefore the conveyor moves the strapped bundle away from the strappingstation.

FIG. 1 is a front isometric view of a conventional strapping machine 10.The strapping machine 10 has several major assemblies, including a feedand tension assembly 15, an accumulator 14, a strap dispenser 30, asealing assembly 40, a track assembly 50, and a control system 60 havingan operator interface region 65. The strapping machine 10 may alsoinclude a frame 70 that structurally supports and/or encloses the majorsubassemblies. The assembly and purposes of the conventional majorassemblies are described in detail in U.S. Pat. No. 6,363,689.

During operation, a strap is moved through the track assembly 50 in thedirection indicated by the arrows 20 before applying the strap to thebundle. Unfortunately, the track assembly 50 includes features, such asexposed edges of strap guides, which interfere with the advancement ofthe strap. For example, an end of the strap can catch on any one of theexposed leading edges of the strap guides during a feed sequence. Thismay cause the strap to become damaged or stuck and may require userintervention to continue the feed sequence. Misfeeds occur when the endof the strap unintentionally passes through gaps along the trackassembly 50. The section of the strap that escapes from the trackassembly 50 is snaked back into the track assembly 50 so that the strapcan be further advanced through the track assembly 50. Once the strap isfed through the track assembly 50, the strap can be drawn from the trackassembly 50 about the bundle adjacent to the sealing assembly 40.

BRIEF SUMMARY

Apparatuses disclosed herein can be used to apply one or more strapsaround a bundle of objects. A variable or constant force can be appliedto tension the strap about the bundle of objects while the strap issealed around the bundle of objects. The apparatus may include astrapping track assembly extending about a strapping station. The trackassembly is adapted to receive a strap during a feed sequence and torelease the strap during a tensioning sequence. The track assembly, insome embodiments, is adapted to reduce or prevent the occurrence ofmisfeeds, such as misfeeds attributable to the end of the strap escapingthrough gaps next to an intended strap path within the track assembly.This ensures that the strap is properly routed through the trackassembly.

In some embodiments, a strapping apparatus for bundling objectscomprises a strapping station and a track assembly. The track assemblyis adapted to receive a strap and to bundle objects at a strappingstation using the strap. The track assembly, in some embodiments,comprises a stationary frame, a first strap guide, a second strap guide,and a corner strap guide interposed between the first and second strapguides. The stationary frame can keep its configuration duringoperation. The first and second strap guides can be linear strap guidesthat extend along a substantially straight axis. A strap path may bedefined between the first strap guide and the frame, the second guideand the frame, and the corner strap guide and the frame. The strap pathcan have a generally rectangular shape, elliptical shape, or any othersuitable shape. In some embodiments, the strap path is a closed looppath.

The corner strap guide can include a leading end and a trailing end. Atrailing end of the first strap guide can be positioned between theleading end of the corner strap guide and a first adjacent section ofthe strap path. The trailing end of the corner strap guide can bebetween a leading end of the second strap guide and a second adjacentsection of the strap path. As such, the strap can slide along the firststrap guide, corner strap guide, and second strap guide without strikingthe upstream end or edges of the strap guides.

The strap guides can be received by one another. In some embodiments,the trailing end of the first strap guide extends into the corner strapguide. The trailing end of the corner strap guide extends into thesecond strap guide. The trailing ends may keep the strap away from theleading edges of the downstream strap guides.

In some embodiments, at least one of the first strap guide, the secondstrap guide, and the corner strap guide tapers inwardly (e.g., towardsthe strap path) in the downstream direction. The tapered strap guidescan position (e.g., center) the strap with respect to downstream strapguides.

Biasing mechanisms can move the strap guides from open positions toclosed positions. In some embodiments, a plurality of biasing mechanismscan cooperate to push the strap guides against the frame. The biasingmechanisms can include one or more springs that cooperate to applydesired forces to the strap guides. If sufficient forces are applied tothe strap, the biasing mechanisms can allow the strap guides to open.

In other embodiments, a track assembly for receiving a strap andbundling objects at a strapping station using the strap is provided. Thetrack assembly comprises an outer frame and a plurality of strap guides.The plurality of strap guides is coupled to the outer frame so as todefine a strap path. In some embodiments, the strap guides are mountedto the inner periphery of the frame. The strap path, in someembodiments, can extend along the length of the track assembly. Eachstrap guide has a trailing end that is disposed between the strap pathand a leading edge of one of the downstream strap guides.

The plurality of strap guides can include a first corner strap guidethat defines a first curved section of the strap path, a second cornerstrap guide that defines a second curved section of the strap path, andan elongate strap guide (e.g., a linear strap guide or an array oflinear strap guides) extending between the first and second corner strapguides. The elongate strap guide can define a substantially linearsection of the strap path. If the outer frame has a substantiallyrectangular shape, the elongate strap guide can extend along one side ofthe frame. In some embodiments, the elongate strap guide is alongitudinally-extending, U-shaped member.

At least one of the strap guides can taper inwardly towards the strappath. In some embodiments, all or most of the strap guides taperinwardly towards the strap path in the downstream direction. Each of thestrap guides can extend partially through an adjacent pair of the strapguides.

In some embodiments, the strap guides may include respective strapretainers. The strap retainers together may extend along nearly all ofthe longitudinal length of the strap path such that a strap moving alongthe strap path is captured between the strap retainers and the outerframe. The strap retainers can cooperate to define a substantiallycontinuous surface along substantially the entire strap path, if neededor desired.

In some embodiments, a strap guide can have a narrowed leading end withrespect to a strap path and a widened trailing end with respect to thestrap path. In some embodiments, for example, a distance betweenopposing sides at the leading end can be less than a distance betweenthe opposing sides at the trailing end.

In some embodiments, a method for passing a strap through a trackassembly is provided. The method comprises moving an end of a strapalong a strap path. The path is positioned between a plurality ofinterconnected strap guides and an outer frame.

In some embodiments, each strap guide has a trailing end that isdisposed between the strap path and a leading edge of one of thedownstream strap guides such that the end of the strap is spaced fromthe leading end of the downstream strap guide. In some embodiments, thestrap guides are interleaved and surround the inner periphery of theframe.

In some embodiments, the end of the strap is passed out of downstreamends of the strap guides disposed within corresponding downstream strapguides. The strap is subsequently used to bundle objects located at astrapping station after moving the end of the strap through the trackassembly. The strap can be tensioned to move the strap guides from afirst position (e.g., a closed position) for retaining the strap to asecond position (e.g., an open position, spread apart configuration,etc.) to allow removal of the strap.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

In the drawings, identical reference numbers identify similar elementsor acts. The sizes and relative positions of elements in the drawingsare not necessarily drawn to scale. The shapes of various elements andangles may not be drawn to scale, and some of these elements may bearbitrarily enlarged and positioned to improve drawing legibility.

FIG. 1 is an isometric view of a conventional strapping machine.

FIG. 2 is a front, top view of a strapping apparatus, in accordance withone embodiment.

FIG. 3 is a front, top view of a strapping track assembly, in accordancewith one embodiment.

FIG. 4 is a front, top view of a strapping track assembly with guardpanels shown removed, in accordance with one embodiment.

FIG. 5 is an isometric view of a portion of the strapping track assemblyof FIG. 4, in accordance with one embodiment.

FIG. 6A is an enlarged pictorial view of a portion of a strapping trackassembly, in accordance with one embodiment.

FIG. 6B is a side elevational view of the interface between two guidemembers, in accordance with one embodiment.

FIG. 7 is a cross-sectional view of the strapping track assembly of FIG.5 taken along line 7-7.

FIG. 8 is a pictorial view of a strap guide member, in accordance withone embodiment.

FIG. 9 is a front elevational view of the strap guide member of FIG. 8.

FIG. 10 is a back elevational view of the strap guide member of FIG. 8.

FIG. 11 is a top plan view of the strap guide member of FIG. 8.

FIGS. 12 and 13 are side elevational views of the strap guide member ofFIG. 8.

FIGS. 14 and 15 are pictorial views of a strap guide member of a cornerstrap guide, in accordance with one embodiment.

FIG. 16 is a front elevational view of a strap guide member of a cornerstrap guide, in accordance with one embodiment.

FIG. 17 is a side elevational view of a strap guide member of a cornerstrap guide, in accordance with one embodiment.

FIG. 18 is an isometric view of a frame of a strapping track assembly,in accordance with one embodiment.

FIG. 19 is a front elevational view of the frame of FIG. 18.

FIG. 20 is a front elevational view of a control system, in accordancewith one embodiment.

FIG. 21 is a side view of operator controls of the control system ofFIG. 20.

DETAILED DESCRIPTION

The present disclosure is directed to, among other things, strappingapparatuses, components and subassemblies of strapping apparatuses(e.g., strapping track assemblies), and methods for strapping bundles ofobjects. Specific details of certain embodiments are set forth in thefollowing description, and in FIGS. 2-21, to provide a thoroughunderstanding of such embodiments. A person of ordinary skill in theart, however, will understand that the disclosed embodiments may haveadditional components and features, and that the embodiments may bepracticed without several of the details described in the followingdescription.

Throughout the following discussion and in the accompanying figures, thestrap material is shown and referred to as a particular type ofmaterial, namely, a flat, two-sided, tape-shaped strip of materialsolely for the purpose of simplifying the description of variousembodiments. It should be understood, however, that several of themethods and embodiments disclosed herein may be equally applicable tovarious types of strap material, and not just to the flat, two-sided,tape-shaped material shown in the figures. Thus, as used herein, theterms “strap” and “strap material” should be understood to include,without limitation, all types of materials used to bundle objects, forexample, synthetic materials, natural materials, metallic materials, orsome other more rigid strap material. One type of strap that may be usedwith all or some of the embodiments described herein is a papercord-type strap comprised of individual round cords laterally bondedtogether to form a continuous strap. The strap may be rigid,semi-flexible, or flexible depending on the application.

FIG. 2 illustrates a strapping apparatus 100 that includes a pluralityof conveyors 110 for moving bundles into and out of a strapping station120, which is surrounded by a strapping track assembly 118. Varioustypes of strapping stations can be employed based on the dimensions ofthe bundles to be strapped. Different types of components (e.g.,tensioning units, sealing head assemblies, etc.) can be located at orproximate to the strapping station 120. Strap employed during bundlingoperations is fed about the strapping track assembly 118 in a strap-feeddirection 119, illustrated in the counter-clockwise direction, along astrap path (e.g., a substantially rectangular or elliptical strap path)within the strapping track assembly 118. A frame 139 for supporting thestrapping apparatus 100 can be temporary or permanently affixed to thefloor. The independently powered conveyors 110 are independentlysupported by conveyor frames 145.

Some of the other major assemblies of the strapping apparatus 100include, without limitation, a control system for programming andcontrolling various functions of the apparatus, an accumulator 96, and afeed and tension unit for receiving and feeding the strap around one ormore bundles on the conveyors 110. The strapping apparatus 100 can befurther configured with a sealing head assembly 98 for sealing the straparound the bundle (not shown). At least some of the major assemblies canbe of modular construction, which allows them to be used in multipleframe configurations or attached as add-on components to existingstrapping machines. The illustrated strapping track assembly 118 has amodular construction for use with a wide range of strapping machines.Various assemblies and components of the strapping apparatus 100 arediscussed in detail below.

FIG. 3 shows the strapping track assembly 118 partially enclosed byspaced apart guard panels 140 a, 140 b (collectively 140) and opposingspaced apart guard panels 142 a, 142 b (collectively 142). Each of theguard panels 140, 142 has cutouts 150, 152 that provide access tocomponents of the strapping track assembly 118. In some embodiments, theguard panels 140, 142 can be easily removed to perform maintenance onthe track assembly 118. A handle 153 may be used to move the entirestrapping apparatus 100, the track assembly 118 with respect to theframe 139, and the like

Referring to FIG. 4, the strapping track assembly 118 (shown with theguard panels 140, 142 removed) may provide the reliability of a fullyenclosed track configuration while reducing, limiting, or substantiallyeliminating problems associated with misfeeds, straps catching on edges(e.g., leading edges) of strap guides, and the like. The illustratedstrapping track assembly 118 includes five linear track sections 201 a-e(collectively 201) and four corner sections 202 a-d (collectively 202).Each of the corner sections 202 is interposed between one pair of thelinear track sections 201 and can be similar to one another.

A plurality of strap guides 220 a-e, 222 a-d is coupled to a rigid frame240 to define a strap path of travel. The strap guides 220 a-e(collectively 220) are elongate strap guides (illustrated assubstantially linear guides) at corresponding track sections 201 a-e,and the strap guides 222 a-d (collectively 222) are corner strap guidesat corresponding corner sections 202 a-d. The strap guides 220, 222 areinterleaved in the feed direction such that the leading edges of thestrap guides 220, 222 do not contact the strap so as to reduce, limit,or substantially eliminate the occurrence of misfeeds, damage to thestrap attributable to the leading edges, and the like. Each of the strapguides 220, 222 can have a trailing end (e.g., a downstream end) thatkeeps the strap from contacting a leading end (e.g., an upstream end) ofone of the adjacent downstream strap guides, as discussed in detailbelow.

As shown in FIG. 5, the corner strap guide 222 d is interposed betweenthe strap guides 220 d, 220 e. A central section 225 of the corner strapguide 222 d extends from the upstream strap guide 220 d to thedownstream strap guide 220 e. In the illustrated embodiment, asubstantial portion of the corner strap guide 222 d extends between theadjacent strap guides 220 d, 220 e.

The corner strap guide 222 d includes a leading end 260 for surroundingthe upstream strap guide 220 d and a trailing end 262 for extending intothe downstream strap guide 220 e. A trailing end 270 of the upstreamstrap guide 220 d is between the leading end 260 of the strap guide 222d and a strap path (discussed in connection with FIGS. 6A, 6B, and 7),and the trailing end 262 of the corner guide 222 d is between a leadingend 272 of the downstream strap guide 220 e and the strap path. Thetrailing ends 270, 262 thus physically separate and protect the strapfrom the respective leading edges 261, 273. This ensures that the edges261, 273 do not cause misfeeds.

Each of the strap guides 220 d, 220 e, 222 d can taper with respect tothe strap path, for example, in the downstream direction. In someembodiments, including the illustrated embodiment of FIG. 5, thenarrowed trailing end 270 of the strap guide 220 d extends into thewidened leading end 260 of the corner strap guide 222 d, and thenarrowed trailing end 262 of the corner strap guide 222 d extends intothe widened leading end 272 of the strap guide 220 e. The narrowedtrailing ends 270, 262 can closely surround and help center the strapwith respect to the downstream strap guides 222 d, 220 e, respectively.

Referring to FIG. 6A, a transverse width W of the leading end 260 isgreater than a length L of the portion of the trailing end 270 withinthe strap guide 222 d. The length L can be measured in the direction ofa strap path 302 aligned with a longitudinal gap 303 extending along theinner periphery of the track assembly 118. The leading end 260 canclosely surround the trailing end 270 while allowing slight relativemovement between the strap guides 220 d, 222 d. The length L of theportion of the leading end 270 within the strap guide 222 d can beselected based on, for example, the desired amount of guide overlap,flexibility of the strap, and ease of assembly. As such, the end of thestrap can move along the strap path 302 past the intersection of thestrap guides 220 d, 222 d (see FIG. 6B) without the strap end passingthrough any gaps between the strap guides 220 d, 222 d. In this manner,strap misfeeds can be avoided.

As used herein, the term “strap guide” can include, but is not limitedto, one or more components adapted to engage and guide a strap along adesired strap path. A strap may slide smoothly between strap guidespositioned along a strap path without damaging the strap. In someembodiments, a strap guide can be a monolithically formed one-piececomponent. In other embodiments, a strap guide can include a pluralityof separate components. For example, the strap guide 220 e of FIGS. 6A,6B, and 7 includes a pair of spaced apart strap guide members 236 a, 236b movable between a closed position 237 and an open position 238 (shownin phantom). Each of the strap guide members 236 a, 236 b includes arespective sidewall 239 a, 239 b and a respective strap retainer 243 a,243 b. The illustrated sidewall 239 a is approximately parallel to thesidewall 239 b when the strap guide 220 e is closed.

FIGS. 8-13 show the strap guide member 236 a that includes the retainer243 a extending substantially perpendicularly from the sidewall 239 a.The retainer 243 a includes a lower engagement surface 247 for slidablycontacting the strap. The sidewall 239 a includes a plurality ofopenings 250 (FIG. 8) through which elongate rods 251 (FIG. 5) orbiasing mechanisms 203 a, 203 b can extend. The openings 250 can beholes, slots, and the like.

As shown in FIGS. 14-17, a strap guide member 238 a of the strap guide222 d includes a sidewall 273 and an arcuate strap retainer 277. Thestrap retainer 277 includes an engagement surface 279 for slidablycontacting the strap. Because the strap guide 220 d is substantiallyperpendicular to the strap guide 220 e (see FIG. 4), the strap retainer277 subtends an angle of about 90 degrees such that the tensioned strapcan curve along the strap retainer 277 between the strap guides 220 d,220 e. Other configurations and curvatures of the strap retainer 277 arealso possible.

With reference again to FIG. 5, biasing mechanisms 203 a, 203 b can biasthe strap guide members 236 a, 236 b to the illustrated closed position.The biasing mechanisms 203 a, 203 b can be generally similar to eachother. The biasing mechanism 203 a includes a spring retainer 241 and abiasing member 239 captured between the spring retainer 241 and theguide member 236 a. The spring retainer 241 can be a free floating capscrew extending outwardly from both sides of the track assembly 118. Thebiasing members 239 can be interposed between the guide members 236 a,236 b and the caps of the spring retainer 241. In some embodiments, theretainer 241 is a floating cap screw and an associated hex nut arecentered about the track 118 by two compression biasing members 239 inthe form of compression springs applying somewhat equal forces. This hasthe effect of providing an equal load on both sides of the strap as thestrap is pulled from the track assembly 118. In other embodiments, thestop 241 is fixedly coupled to the frame 240 such that the biasingmember 239 presses the strap guide member 236 a against the frame 240.The biasing member 239 can be in the form of one or more springs (e.g.,helical springs, coil springs, etc.), elastically compressible members,and the like. Other types of biasing members can also be used.

Referring to FIGS. 5 and 7, the biasing mechanisms 203 a, 203 b may holdthe strap guide 220 e proximate to or against the outer frame 240 so asto form a partially or fully enclosed channel 300. The strap path 302(shown in phantom line in FIGS. 6A and 7) extends longitudinally alongthe open channel 300. A strap 304, shown in phantom line in FIG. 7, canmove along the strap path 302 through the track assembly 100. The edgesof the strap 304 can slide along the strap retainers 243 a, 234 b. Assuch, the strap path 302 can be defined, at least in part, by the strapguides 220, 222 and the frame 240, as well as other components suitablefor contacting the strap.

With reference to FIGS. 6A, 6B, and 7, the strap retainers 243 a, 243 bare spaced from an engagement surface 283 of the frame 240. The strap304 can be captured between lower surfaces of the strap retainers 243 a,243 b and the surface 283. The illustrated strap 304 is spaced from theengagement surface 283.

Each of the plurality of strap guides 220, 222 can include one or morestrap retainers that extend along nearly all of their respectivelengths. The strap retainers can extend along nearly all, or all, of thelength of the strap path 302. In some embodiments, the strap retainerscollectively extend along at least 95%, 90%, or 80% of the length of thestrap path 302 defined by the strapping strap assemble 118. Suchembodiments ensure that the strap is properly guided along a substantialportion of the strap path 302.

With respect to FIGS. 18 and 19, the frame 240 includes a pluralityinterlocked elongate frame sections 301 a-e (collectively 301) andcorner frame sections 302 a-d (collectively 302). The assembled tracksections 201 are formed by the respective frame sections 301 and strapguides 220 movable with respect to the frame sections 301. The cornertrack sections 202 are formed by the respective corner frame sections302 and the strap guides 222 movable with respect to the corner framesections 302. In other embodiments, the frame 240 can have a one-piececonstruction. Such embodiments may be more rigid than the multi-pieceframe 240 illustrated in FIGS. 18 and 19.

Various types of production cycles can be performed using the strappingtrack assembly 118. During the tensioning cycle, a sealing head assembly98 grips the free end of the strap and a feed/tension unit begins totension the strap around the product surrounded by the strapping trackassembly 118. As the strap is drawn back by the feed/tension unit, theforces may overcome the bias of the biasing mechanisms 203 a,b to causethe closed strap guides 220, 222 to move (e.g., pivot) to the openpositions, thereby allowing the strap to escape from the separated strapguides 220, 222. As the strap forces the track sections 220, 222 open,each successive set of strap guides 220, 222 are urged open by theprevious set of strap guides, thereby providing a controlled release ofthe strap. The amount of overlap between the strap guides 220, 222 canbe selected such that the strap guides open together. During thetensioning cycle, the interleaved track design also has the advantage ofhaving few or no gaps between strap guides to catch the strap edges andto reduce the occurrence of the strap escaping from the track assembly118.

The strapping apparatus 100 can be controlled by a control system 800illustrated in FIG. 20. The control system 800 can be mounted orincorporated into the accumulator 96 and may include a programmablelogic controller (PLC) 802 which operates in conjunction with variousinput and output devices and controls the major subassemblies of thestrapping apparatus 100. Input devices may include, for example,momentary and maintained push buttons, selector switches, toggleswitches, limit switches, photoelectric sensors, and inductive proximitysensors. Output devices may include, for example, solid state andgeneral purpose relays, solenoids, and indicator lights. Input devicesare scanned by the controller 802, and their on/off states are updatedin a controller program. The controller 802 executes the controllerprogram and updates the status of the output devices accordingly. Othercontrol functions of the controller 802 are described below in furtherdetail.

In some embodiments, the programmable controller 802 and its associatedinput and output devices may be powered using a 24 VDC power supply. Thecontroller 802, power supply, relays, and fuses may be contained withina control panel, as illustrated in FIG. 21. The momentary and maintainedpush buttons, selector switches, and toggle switches 810 may be locatedon the control panel. The limit switches, inductive proximity sensors,photoelectric sensors, and solenoids are typically located within thestrapping apparatus 100 at their point of use. An indicator light stackmay be mounted on the top of the arch indicating a strap mis-feed,out-of-strap, normal running or machine malfunction condition, forexample.

One commercially-available PLC 802 suitable for use with the strappingapparatus 100 is the MICROLOGIX 1500 manufactured byAllen-Bradley/Rockwell. This device includes PNP digital and relay typeoutputs. In addition the PLC utilizes input and output cards tointerface to external production line equipment control system and tofour machine mounted motors (e.g., Dunkermotoren BG75 servomotors) whichdrive the accumulator 96, feed and primary tension, secondary tensionand sealing head functions. One skilled in the art will understand thatanother industry standard PLC may also be used in place of the PLCdescribed above.

The MICROLOGIX 1500 PLC 802 has communication ports, including an RS232Cport for program uploads, downloads and monitoring and a RS232C port forconnection to an EZ-AUTOMATION HMI (Human-Machine-Interface) 812 mountedto the control panel side. The HMI provides machine diagnostics andoperational data (e.g., number of straps applied, sensor status, etc.)in addition to providing operational parameter selections (e.g., strapposition on the bundle, number of straps per bundle, etc.).

The operation of the strapping apparatus 100 may involves pulling strapfrom a dispenser and feeding a free end of the strap through theaccumulator 96, through the feed and tension unit, up through thesealing head assembly 98, and then around the strapping track assembly118. U.S. application Ser. No. 12/072,107 discloses these components andtheir functionality. Because the track assembly 118 is adapted tominimize or limit the occurrence of misfeeds and/or damage to the end ofthe strap due to unwanted large gaps between strap guides, strap can beconsistently fed through the track assembly 118. After the strap is fedaround the strapping track assembly 118, the free end is guided backinto the sealing head assembly 98. At this point, the strap is inposition to start a strapping cycle where the strap can be tensioned andsecured about a bundle of objects.

In operation, during a tensioning or bundling operation, the tensioningof the strap occurs in two stages, a primary tension stage and asecondary tension stage. In the primary tensioning stage, the strap ispulled out of the track assembly 118 and, in some processes, down ontothe bundle of objects. The secondary tensioning sequence involvesbinding the strap tightly around the bundle of objects located in thestrapping station 120. After the strap is tensioned to the point that aservomotor stalls, a controller permits a predetermined amount of timeto pass so as to allow the sealing head assembly 98 to rotate to gripthe strap. After securing the strap, the tension is released just priorto cutting the strap from the supply to prevent the strap from fraying.The strap is then cut and sealed. Once the sealing operation iscomplete, the feeding sequence may then be repeated.

The primary tensioning sequence provides enough force on the strap topull the strap inwardly away from the frame 240 and through thelongitudinal openings 303 provided by the strap guides 220, 222. As thestrap is tensioned around the bundle of objects, the straight and cornertrack guides 220, 222 can be opened by the strap 102, allowing the strapto pull clear of the channel 300. The force applied to the strap canovercome the biasing of the biasing mechanisms for convenient opening ofthe strap guides 220, 222. The strapping track assembly 118 may beconfigured to permit controlled sequential strap removal from the strapguides 220, 222, thereby reducing, limiting, or substantiallyeliminating damage to the strap. After the strap clears the channel 300,the strap is pulled around a bundle of objects and both the straight andcorner track guides 220, 222 close because of the biasing mechanisms.

Once the strap has been sufficiently tensioned around the bundle ofobjects, the non-free end of the strap can be cut and then both ends ofthe strap can be sealed together. The sealing operation commences whenseveral sealing head cams in the sealing head assembly 98 begin torotate, forcing a gripper to pinch the free end of the strap against ananvil. Those skilled in the art will recognize that the strappingapparatus 100 can be configured, depending on strap orientation, toaccommodate the same gripper on the opposite side. After gripping thefree end of the strap in the sealing head assembly 98, the feed andtension unit retracts the excess strap from the track assembly 118(i.e., the tensioning operation discussed above).

In one embodiment, the strap used to bundle objects can have aheat-activated adhesive applied thereon. Preferably, the adhesive on thestrap is applied to the strap during the manufacturing process of thestrap. Heat is applied to the strap by inserting a heater blade betweenthe two overlapping ends of the strap and lightly pressing the endsagainst the blade by raising a press platen. Various types of furtherprocessing can be performed on the strap to ensure that strap isproperly secured. At this point, the strapping track assembly 118 isready for the strap to be fed again.

Except as described herein, the embodiments, features, systems, devices,materials, methods and techniques described herein may, in someembodiments, be similar to any one or more of the embodiments, features,systems, devices, materials, straps, methods and techniques described inU.S. Patent Publication No. 2004/0200191, U.S. patent application Ser.No. 12/072,107, and U.S. Provisional Patent Application No. 60/921,022.In addition, the embodiments, features, systems, devices, materials,methods and techniques described herein may, in certain embodiments, beapplied to or used in connection with any one or more of theembodiments, features, systems, devices, materials, methods andtechniques disclosed in the above-mentioned U.S. Patent Publication No.2004/0200191 and U.S. Provisional Patent Application No. 60/903,230.U.S. Patent Publication No. 2004/0200191, U.S. patent application Ser.No. 12/072,107, and U.S. Provisional Patent Application No. 60/921,022are hereby incorporated by reference herein in their entireties.

Although specific embodiments of, and examples for, the invention aredescribed herein for illustrative purposes, various equivalentmodifications are possible within the scope of the invention, as thoseskilled in the relevant art will recognize. The teachings providedherein of the invention can be applied to other methods and apparatusfor strapping bundles of objects, and not just to the methods andapparatus for strapping bundles of objects described above and shown inthe figures. In general, in the following claims, the terms used shouldnot be construed to limit the invention to the specific embodimentsdisclosed in the specification. Accordingly, the invention is notlimited by the foregoing disclosure, but instead its scope is to bedetermined by the following claims.

1. A strapping apparatus for bundling objects, comprising: a strappingstation; and a track assembly adapted to receive a strap and to bundleobjects at the strapping station using the strap, the track assemblycomprising a stationary frame, a first linear strap guide, a secondlinear strap guide, and a corner strap guide interposed between thefirst and second linear strap guides, a strap path defined between theframe and the first linear strap guide, the second linear strap guide,and the corner strap guide, a trailing end of the first linear strapguide extending downstream along the strap path past at least a portionof a leading end of the corner strap guide, a trailing end of the cornerstrap guide extending downstream past a portion of a leading end of thesecond linear strap guide.
 2. The strapping apparatus of claim 1,wherein the trailing end of the first linear strap guide extends betweenthe leading end of the corner strap guide and the strap path, thetrailing end of the corner strap guide extends between the leading endof the second linear strap guide and the strap path.
 3. The strappingapparatus of claim 1, wherein at least one of the first linear strapguide, the second linear strap guide, and the corner strap guide tapersinwardly towards the strap path in a down stream direction.
 4. Thestrapping apparatus of claim 1, further comprising: at least one biasingmechanism coupled to the frame, the at least one biasing mechanism movesone of the first linear strap guide, the second linear strap guide, andthe corner strap guide from an open position for releasing a straptowards a closed position for capturing a strap.
 5. The strappingapparatus of claim 1, wherein the trailing end of the first linear strapguide extends through the leading end of the corner strap guide.
 6. Atrack assembly for receiving a strap and bundling objects at a strappingstation using the strap, the track assembly comprising: an outer frame;and a plurality of strap guides for releasably retaining a strap, theplurality of strap guides coupled to the outer frame so as to define astrap path located between the plurality of strap guides and the frame,each strap guide having a trailing end disposed between the strap pathand a leading edge of a downstream strap guide such that a strap movingalong the strap path is spaced from the leading edge of the downstreamstrap guide.
 7. The track assembly of claim 6, wherein the plurality ofstrap guides includes a first corner strap guide that defines a firstcurved section of the strap path, a second corner strap guide thatdefines a second curved section of the strap path, and an elongate strapguide extends between the first and second corner strap guides anddefines at least a portion of a substantially linear section of thestrap path connecting the first and second curved sections.
 8. The trackassembly of claim 6, wherein each of the plurality of strap guides hasat least one strap retainer positioned interior of the frame to define achannel between the strap retainers and the frame, the strap pathextending along the channel.
 9. The track assembly of claim 6, whereinthe outer frame and the strap path have a substantially rectangularshape.
 10. The track assembly of claim 6, wherein one of the strapguides is a curved strap guide interposed between two of the strapguides that are linear strap guides.
 11. The track assembly of claim 10,wherein the linear strap guides are substantially perpendicular to oneanother.
 12. The track assembly of claim 6, wherein at least one of thestrap guides tapers inwardly towards the strap path in the downstreamdirection.
 13. The track assembly of claim 6, wherein each of the strapguides has a widened end and an opposing narrowed end.
 14. The trackassembly of claim 6, wherein each of the strap guides extends partiallythrough an adjacent pair of the strap guides.
 15. The track assembly ofclaim 6, wherein a length of a portion of a strap guide extending intoan adjacent strap guide is less than a transverse width of a strappositioned along the strap path and captured the plurality of strapguides.
 16. The track assembly of claim 6, wherein at least one of thestrap guides has a narrowed leading end with respect to the strap pathand a widened trailing end with respect to the strap path.
 17. The trackassembly of claim 6, wherein each of the plurality of strap guidesincludes respective strap retainers, the strap retainers together extendalong nearly all of a longitudinal length of the strap path such that astrap positioned along the strap path is captured between the strapretainers and the frame.
 18. The track assembly of claim 17, wherein thestrap retainers extend alongside substantially all of the longitudinallength of the strap path.
 19. The track assembly of claim 6, wherein thestrap guides are interleaved with one another.
 20. The track assembly ofclaim 6, wherein each of the plurality of strap guides has a closedposition for retaining a strap positioned along the strap path and anopen position to allow the strap to move out of the respective strapguides.
 21. A method for passing a strap through a track assembly, themethod comprising moving an end of a strap along a strap path locatedbetween a plurality of strap guides and an outer frame, each strap guidehaving a trailing end that is disposed between the strap path and aleading edge of a downstream strap guide such that the end of the strapis separated from the leading end of the downstream strap guide by thetrailing end of an upstream strap guide as the end of the strap is moveddownstream past the leading edge.
 22. The method of claim 21, whereinmoving the end of the strap further comprises sequentially moving theend of the strap out of trailing ends of the strap guides disposedwithin corresponding downstream strap guides.
 23. The method of claim21, further comprising: surrounding a bundle at a strapping stationusing the strap from the track assembly after moving the end of thestrap along the strap path and through the track assembly.
 24. Themethod of claim 21, further comprising: moving the strap out of thestrap guides by moving the strap guides from closed positions to openpositions.